Adaptive Fuzzy PID Temperature Control System bad on Single-chip
Computer for the Autoclave
峡组词F. ZHANG a J. WANG a S. L. FU b* Z. T. HE a X. P. LI a
a College of Vehicle ＆Motive Power Engineering, Henan University of Science and Technology,
471003, Luoyang City, P. R. China; b College of Science, Henan University of Science and
Technology, 471003, Luoyang City, P. R. China
ABSTRACT
The autoclave is one of main preparation equipments of crystal preparation by hydrothermal method. The preparation temperature will riously influence crystals quality and crystals size at high temperature, how to measure and control precily the autoclave temperature can be of real significance. The characteristic of hysteresis, nonlinearity and difficulty to acquire the preci mathematical model existing in the temperature control of the autoclave was rearched. The general PID controller adopted usually in the autoclave temperature control system is hard to improve temperat
ure control performance. Bad on the advantages of fuzzy controller that does not depend on the preci mathematical model and the stabilization of PID controller, single-chip computer integrated fuzzy PID control algorithm is adopted, and the temperature system is designed, the foundational working principle was discusd. The control system includes SCM (AT89C52), temperature nsor, A/D converter circuit and corresponding circuit and interface, can make the autoclave temperature measure and control accurately. The system hardware includes main circuit, thyristor drive circuit, audible and visual alarm circuit, watchdog circuit, clock circuit, keyboard and display circuit so on, which can achieve gathering, analyzing, comparing and controlling the autoclave temperature parameter. The program of control system includes the treatment and collection of temperature data, the dynamic display program, the fuzzy PID control system, the audible and visual alarm program, et al, and the system’s main software, which includes initialization, key-press processing, input processing, display, and the fuzzy PID control program was analyzed. The results showed that the fuzzy PID control system makes the adjustment time of temperature decread and the precision of temperature control improved, the quality and the crystals size of the preparation crystals can achieve the expect experiment results.
Keywords: The Autoclave; Temperature Control; Crystal Preparation; Fuzzy Control; PID Control
1.INTRODUCTION
Hydrothermal method is a way to obtain crystals in the high temperature and high pressure aqueous solution. Crystals synthesized by hydrothermal method are characterized by high quality, low thermal stress, less defects, homogenous doping and good performance [1,2]. SnO2 is an n-type miconductor with a direct band gap of 3.6 eV between the full oxygen 2p valence band and the tin states at the bottom of the conduction band. It has received intensive interests for its
* corresponding author: Sanling Fu; E-mail: ; phone: +86-0379********
Fourth International Symposium on Precision Mechanical Measurements, edited by Yetai Fei, Kuang-Chao Fan, Rongsheng Lu, Proc. of SPIE Vol. 7130, 71302G · © 2008 SPIE · CCC code: 0277-786X/08/$18 · doi: 10.1117/12.819628
applications in solar cells [3,4], catalysis [5], and transparent electrodes [6,7], especially in combustible and toxic gas detection devices (gas nsors) [8,9].
The preparation temperature of hydrothermal method will riously influence crystal quality and crystals size of SnO2 when the SnO2 crystals were prepared at high temperature. The SnO2 crystal
s with the diameter of 10～20nm and the length of 100nm are synthesized at 180℃ and the rutile-type SnO2 crystals with the length of 200nm are synthesized at 430℃, so how to measure and control the preparation temperature can be of real significance.望野
In the rearch work, the adaptive fuzzy PID temperature control system for the autoclave was designed bad on single-chip computer, the system can effectively solve the influence of thermal inertia on the accuracy of temperature control, and solve the lower qualification rates of SnO2 nanocrystal, so the SnO2 nanocrystal structure and crystal high quality can be achieved.
2.THE BASIC OPERATING PRINCIPLE AND SYSTEM HARDWARE COMPONENT乡村路
The voltage signal of the temperature in the autoclave can be collection by Pt200 temperature nsor, and the voltage signal of the temperature is amplified by operational amplifier, the single chip microcomputer can process the binary data of 8 bit from A/D conversion of the analog signal of the temperature. The microcomputer will distinguish the logistic request bad on the design temperature by ur. The control parameters was obtained by fuzzy PID control algorithm subprogram, the PWM output on-off signal of the microcomputer insulated and treated will directly drive bidirectional thyristor which control the resistance wire power of the autoclave, so the autoclave
temperature was controlled. The microcomputer can protect spot by the Bidirectional thyristor element if the autoclave temperature is out of the order, and the power of the autoclave switched off. The buzzer gives an alarm to the ur and the LED will display the temperature fault. The ur can e the real-time temperature of the autoclave through the LED display regardless of natural run state or fault state of the equipment. The ur can modify the function parameters of the equipment by the keyboard bad on the necessary state. The hardware system sketch of the control and measure system of the temperature is shown in Fig. 1.
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Fig. 1 The hardware system sketch of the control and measure system of the temperature
华浦英语The hardware of the measure and control system of the autoclave temperature includes: single chip microcomputer (AT89C52), A/D converter (AD0809), clock circuit (DS12887), watchdog circuit (X5045) and photoelectric isolator (MOC3041), et al.
3. THE DESIGN PRINCIPLE OF ADAPTIVE FUZZY PID TEMPERATURE CONTROL
SYSTEM
3.1 The structure of adaptive fuzzy PID temperature control system
The adaptive fuzzy PID [10,11] temperature control system was compod of PID with controllable parameters and fuzzy control system, the control principle of the system was showed as Fig.2. The PID with controllable parameters can complete system control, and the fuzzy system can solve automatic correction for three PID parameters.
Generally, the Digital PID controller can be expresd by function as follows:
10()()()()K
Pe c j u k K k K e i KDe k ==++∑
In the formulas, where, ()e k is the system erro; ()c e k is the Range Rate of system error;
p K is coefficient in physical formulas; I K is integral action coefficient; D K is differential action coefficient.
Fig. 2 The control principle of the system
3.2 The membership of individual variable determined The two-input and three-output form was ud by the fuzzy controller of PID lf-turning parameters. e and ec are the input parameters , and P K ,
I K and D K are the output parameters. The discour domain of input program variables was ﹛-6, -5, -4, -3, -2, -1, 0, 1, 2, 3, 4 5, 6﹜, The discour domain of output program variables was ﹛0, 1, 2, 3 4, 5, 6﹜, the membership parameters of individual variable were showed as Fig. 3 and Fig.
4.
Fig. 3 The membership parameters with e and ec Fig. 4 The membership parameters with K P, K I and K D
3.3Fuzzy reasoning table established.
The control principles of the output parameters included K P, K I and K D were concluded bad on adjustment principle of PID parameters, and the fuzzy control principles were showed as Table 1, Table2 and Table3.
Table 2 The fuzzy control principle table of K
Table 1 The fuzzy control principle table of K
Table 3 The fuzzy control principle table of K
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4.THE DESIGN OF SOFTWARE SYSTEM
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The main program had completed the initialization of the system, the temperature digital gathering, the fuzzy PID algorithm program calling, the heater on-off control, etc. The flow chart of main progra
m was showed as Fig. 5. The fuzzy PID control algorithm subprogram had completed current temperature sampling, temperature deviation, temperature deviation rate, obfuscation, PID parameters, etc. The flow chart of fuzzy PID control algorithm subprogram was showed as Fig. 6.
Fig. 5 The flow chart of main program Fig. 6 The flow chart of fuzzy PID control algorithm subprogram
5.RESULTS AND CONCLUSIONS印度环蛇
The comparison figures between the ca with PID control and that without PID control at 180℃were showed as Fig. 7
and Fig. 8. The SnO2 nanocrystal by hydrothermal method bad on the adaptive fuzzy PID temperature control system is similar to the SnO2 nanocrystal in the document [12], however, the SnO2 nanocrystal by hydrothermal method without PID temperature control system is dissimilar to the SnO2 nanocrystal in the document, so the fuzzy PID control system makes the adjustment time of temperature decread and the precision of temperature control improved, the quality and the crystals size of the preparation crystals can achieve the expect experiment results.
Fig. 7 The SnO2 nanocrystal by hydrothermal method
without PID temperature control system at 180℃
Fig. 8 The SnO2 nanocrystal by hydrothermal method bad
on the adaptive fuzzy PID temperature control system at
180℃
